Mechanisms of ultrasound-synergized polyphenol enhancing the foaming properties of ovalbumin: Focus on interfacial behavior and microstructure

• Ultrasound effectively increased the thickness of gas-liquid interface film. • Polyphenols promoted uniform OVA adsorption at the interface, forming compact foam. • Ultrasound-synergized polyphenol made OVA structure more extended and disordered. • PA binds to OVA via polar hydrogen bonds, SA binds via van der Waals and C-H bonds. • The higher molecular weight of polyphenol, the stronger their affinity for protein. This study thoroughly analyzed the mechanism by which ultrasound-synergized polyphenol treatment to improve the foaming properties of ovalbumin (OVA) from perspectives of physicochemistry and structure. The results demonstrated that ultrasound-synergized protocatechuic aldehyde (PA) or syringic acid (SA) enhanced the foaming ability (FA) of OVA by 27.5% and 34.5%, respectively, and foam stability (FS) increased by 5.5% and 3.7%. SA with a larger molecular exhibited stronger affinity to OVA, facilitating superior adsorption at the air-water interface and producing a more uniform and dense foam microstructure. Physicochemical characterization revealed that ultrasound-synergized polyphenol treatment increased the aggregation of soluble particles in the systems, improving solubility, surface hydrophobicity and thermal stability. The results of protein structure illustrated that PA bound to OVA through more polar hydrogen bonds, whereas SA bound to OVA via weaker polar van der Waals forces and carbon-hydrogen bonds. These findings suggested that polyphenol-protein interactions characterized by higher molecular weight and lower polarity favor enhanced foaming properties. Therefore, ultrasound-synergized polyphenol treatment is an effective strategy for improving OVA foaming properties. This study provides valuable insights into the mechanisms underlying improvement of protein foaming properties and offers a theoretical foundation for practical applications.